SORU: boş bırakılan yere parçanın anlam bütünlüğünü sağlamak için getirilebilecek cümleyi bulunuz
As the hardest substance known, diamond is ideal for cutting rock and other tough stuff. ---- For cutting steel, the first choice is cubic boron nitride, which is almost as hard. But manufacturing the substance requires high temperatures and extreme pressures, which make it expensive.